The beneficial properties of fluoropolymers are well known in the art and include for example, high temperature resistance, high chemical resistance including for example high resistance to solvents, fuels and corrosive chemicals, and non-flammability. Because of these beneficial properties, fluoropolymers find wide application particularly where materials are exposed to high temperature and/or chemicals.
For example, fluoropolymers are used in fuel management systems which include for example fuel tanks, fuel filler lines and fuel supply lines in cars or other motor vehicles because of their excellent resistance to fuels and because of the good barrier properties that can be achieved with fluoropolymers. Additionally, fluoropolymers, in particular fluoroelastomers, may be used in a hose connecting the compressor of a turbo engine with an intercooler. Because of the high temperature of the compressed air, non-fluorine elastomers such as ethylene acrylic based elastomers or silicone elastomers cannot be used for such a hose.
Fluoropolymers are generally more expensive than non-fluorine polymers and accordingly, materials have been developed in which the fluoropolymer is used in combination with other materials to reduce the overall cost of an article. For example, in the aforementioned hose used in turbo engines, it has been proposed to use a relatively thin layer of fluoroelastomer as an inner layer of a multilayer hose where the outerlayer of the hose is then a non-fluorine elastomer such as for example a silicone elastomer. It is required in such a multilayer hose that the fluoropolymer layer be firmly and reliably bonded to the other layers of the hose. Unfortunately, bonding of fluoropolymers to other substrates is often difficult and in particular bonding to silicone elastomers has been found difficult. This is further complicated by the fact that various silicone compositions exist such that in one instance a particular fluoropolymer composition may show good bonding, yet in another instance satisfactory bonding may not be obtained. To solve this problem, tie layers have been proposed between the fluoropolymer and other materials such as a silicone elastomer, but this increases cost and makes the manufacturing more complicated.
A further application in which a multi-layer article including a fluoropolymer layer is used is in a fuser member of a plain paper copier. Such a fuser member typically has a thermally conductive silicone elastomer which is bonded to a fluoroelastomer surface layer which may also include conductive particles. Such a fuser member is disclosed in for example U.S. Pat. No. 5,217,837. This U.S. patent describes a multilayer fuser member in which the silicone elastomer is bonded to the fluoroelastomer with the intermediate of an adhesive layer. The manufacturing of such a fuser member is unfortunately cumbersome. A similar system is described in U.S. Pat. No. 6,020,038.
Further, in certain applications, it may further be desirable to bond fluoropolymers of different nature and composition to each other. For example, in a fuel supply line, it may be desirable to bond a fluoroelastomer layer to fluorothermoplastic polymer layer. Although both polymers are fluoropolymers, desired bond strength may still not be achieved.
Accordingly, it would be desirable to find a way of improving bonding of a fluoropolymer to other substrates such as for example non-fluorine elastomers, silicone rubbers and other fluoropolymers. Preferably, this solution is cost effective, convenient and reliable and can be applied to a wide variety of substrates.